When camera clipping planes won't render

You've set up manual clipping planes on your camera, these are correctly clipping in the viewport, but they are ignored when you render using the mental ray renderer. When you render with the scanline renderer all is fine.

For this to work as expected you have to make sure that the Scanline option in the mental ray renderer is enabled. In the Render Setup dialog go to the Renderer tab and make sure that in the Rendering Algorithms the Scaline Enable checkbox is ticked: